UPDATE: POLICE have charged a 62-year-old man over an attack on a mother in Perth's south east yesterday.

Anneliese says she with her 15-month-old son while walking with her dogs on Henley Drive in Champion Lakes at 3.30pm when a man jumped out from behind a bush and grabbed her from behind by her pants.

She screamed and the man let go and ran off. He was last seen running in the general direction of a nearby caravan park.

"I couldn't sleep because whenever I closed my eyes all I could see was that man and it's just the most scary and heartbreaking thing to happen," told Seven News.

"The dogs were growling and that didn't even stop him.

"So if I didn't have the dogs, which I normally don't, he could have got me and who knows what would have happened to my son."

Armadale police this afternoon charged a man from Champion Lakes with deprivation of liberty, aggravated indecent assault and committing an act likely to endanger the life, health or safety of any person.